This application is based on patent application Nos. 11-68876, 11-70768 and 11-70769 filed in Japan, the contents of which are hereby incorporated by references.
This invention relates to a sheet transport device for transporting sheets such as documents and copy paper (hereinafter, also simply referred to as xe2x80x9csheetxe2x80x9d) for use in a copier, printer, facsimile machine, scanner and so forth.
Heretofore, a sheet transport device for transporting sheets for use in, for example, a copier, has been provided with a transport path constituting a pair of transport planes disposed opposing to each other. Sheets are successively transported along the transport path in a specified order.
In the above conventional sheet transport device, a smooth sheet transport may be obstructed and a desirable transport state may not be accomplished depending on the configuration of the transport path. For instance, in the case where the transport path has a curved portion or a narrowed region, it is highly likely that the sheet being transported is stuck at the portion, thereby resulting in a folded lead end of the sheet or that the sheet is forcibly transported in a frictional state with the transport plane, thereby generating a smear on the sheet in the case where the sheet is copy paper for image formation. In a worst case, a sheet jam may occur in the transport path.
It is an object of the present invention to provide a sheet transport device that enables to securely accomplish a desired sheet transport state while preventing a drawback such as generation of a folded or bent lead end of a sheet and a sheet jam by applying a transport backup force to the sheet in a sheet transport direction along a sheet transport path.
In order to fulfil the above objects, in accordance with the present invention, a sheet transport device for transporting a sheet along a transport path comprises a projecting tab projecting inwardly in the transport path with such a configuration as to guide the sheet in a specified transport direction, the projecting tab including a contact portion to be in contact with the sheet to form a wavy surface on the sheet in a width direction substantially orthogonal to the specified transport direction.